# Berlin 2012 – wissenschaftliches Programm

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# KR: Fachgruppe Kristallographie

## KR 7: Joint Session "Soft X-ray Resonant Scattering for Complex Structural and Magnetic Investigations" (MA jointly with KR), Organization: Eberhard Goering (MPI-IS Stuttgart)

### KR 7.4: Topical Talk

### Mittwoch, 28. März 2012, 11:15–11:45, BH 243

**Theory of resonant x-ray spectroscopy** — •M. W. Haverkort — Max-Planck Institute for Solid State Research, Stuttgart, Germany

Within the first half of this talk I will review the theoretical interpretation of x-ray absorption spectroscopy (XAS), elastic resonant x-ray diffraction (RXD) and resonant inelastic x-ray scattering (RIXS). I will briefly review how XAS can be used to measure the element specific magnetic susceptibility separated to its spin and orbital momentum contributions. Either with the use of sum-rules or by comparison to theory. Next, I will show how with the use of the optical theorem this understanding of XAS can be extended to RXD. This gives access to measure in a quantitative way the element resolved ordered spin and orbital moments. I will then continue to discuss RIXS, an inelastic scattering technique, which due to recent experimental improvements, allows one to measure dispersing magnetic excitations in small samples and thin films. Using the relations between inelastic scattering, elastic scattering and absorption spectroscopy a quantitative theory for RIXS is derived, which allows for an interpretation of the RIXS spectra very similar to Neutron spectroscopy.

In the last half of the talk several experimental results will be presented which show how these techniques can be used to gain understanding in the magnetic interactions in transition metal compounds.